Faults in concrete structures have long been a problem area for civil engineers. Repair work was often difficult due to the lack of an appropriate material to fill the void and prevent further cracking of the structure. As the faults worsened in condition, the structures (such as bridges, buildings, roads, etc.) had to be completely replaced at great cost. Additionally, cracks are formed at cold joints or abutting concrete wall structures.
Recently, it has been discovered that by injecting an epoxy compound into the void of the fault, the fault may be sealed and further cracking inhibited. The major problem with epoxy is that it hardens very quickly and, therefore, the base and catalyst resins cannot be mixed until just prior to application. Since many fault cracks are only 0.010 to 0.001 inches wide and therefore must be filled with material under high pressures (300 psi and above), special dispensing machines were developed to first mix the epoxy resins then discharge the mixture under high pressure. Prior machines utilized gear pumps which were inefficient due to gear slippage under high pressure. Portable piston pumps have been used but are either not accurate or efficient when injecting epoxy resins at high pressure or require higher than normally expected maintenance and part replacement.